Numerical analysis of a cooling of a hot plate by an array of microjets

Institute of Heat Engineering, Faculty of Power and Aeronautical Engineering, Warsaw University of Technology, 21/25 Nowowiejska St., 00-665, Warsaw, Poland

^* Corresponding author: piotr.lapka@pw.edu.pl

Abstract

In this paper heat transfer during impingement of an array of 8×8 microjets on a hot surface was investigated. The influence of a ratio of a distance between a nozzle and hot plate (H/d) and microjet diameter-based Reynolds number (Red) on the temperature and heat transfer coefficient (HTC) on the hot plate were numerically studied. The numerical model which was based on the steady-state compressible Navier-Stokes equations and SST k-ω turbulence model was developed and applied for the analysis. During simulations the ratio of the distance between the nozzle and hot plate to the microjet diameter was H/d = 3.125, 25 and 50, while the microjet diameter-based Reynolds number was equal to Red = 690, 1100 and 1510. The ratio of the microjet pitch to the microjet diameter was s/d = 31.25. It was found that both the H/d ratio and Red significantly influenced flow patterns in the gap between the nozzle and hot plate as well as the temperature and HTC on the surface of the hot plate. With increase of the H/d ratio a more uniform distributions of the plate temperature and HTC were observed, while the rise in the Red intensified heat transfer on the hot plate.